1. Field of the Invention
The present invention relates to methods and devices for forming microcultures within porous media. Specifically, the present invention relates to methods and materials for: 1) capturing, collecting, or isolating various bacteria and other microorganisms from aqueous environments in the form of biofilms for the purpose of characterization of community structure or identification of specific organisms or 2) concentrating and/or immobilizing specific types of bacteria and/or other microorganisms for the purpose of holding or retaining same within a bioreactor environment. The present invention may be used to capture, collect, or isolate bacteria and other microorganisms in the form of representative biofilms from water sources, such as streams, lakes, reservoirs, and groundwater as well as other aqueous environments such as drinking water or wastewater treatment systems, cooling towers, storage tanks, or any commercial or industrial process which employs or produces an aqueous phase. The present invention may also be used to concentrate and/or immobilize selected bacteria or other microorganisms within a bioreactor and thereby increase the volumetric productivity of the bioreactor. The present invention is a significant improvement over existing technology in that 1) biofilms form rapidly in the present invention and biofilms are more indicative of the operative microbiology of the aqueous environment to which the invention is exposed and 2) the present invention can also make the concentrated or immobilized state the preferred state over the planktonic or “free-floating” mode of existence for specific microorganisms in a bioreactor environment, thereby concentrating and retaining specific types of microorganisms within a bioreactor and thereby concentrating the biocatalytic activity of same and improving the performance of the bioreactor.
2. Prior Art
For a variety of reasons, it is highly desirous to have efficient, accurate, and sensitive methods of detecting, characterizing, and/or identifying microorganisms from aqueous environments. Water treatment facilities for preparing potable water, sewage and wastewater treatment facilities, environmental engineers, ecologists, biologists, and the agriculture industry, to name a few, all require a fast and accurate method for determining the characteristics of operative microbial communities and/or the presence of specific types of microorganisms in aqueous systems.
Microorganisms in aqueous environments have a natural affinity for solid surfaces and commonly form biofilms with complex community structures. Biofilms can concentrate nutrients, exclude toxic substances, facilitate beneficial cross feeding, and promote other interactions between microorganisms that benefit the members of the community. Therefore, microorganisms generally prefer biofilms over the planktonic or “free-floating” state. Planktonic microorganisms in an aqueous environment are generally those that have not yet been taken up by biofilms or sloughed off from biofilms as the biofilms grow in size. It has been frequently observed that the physiology of many microorganisms is different in biofilms compared to planktonic or “free-floating” organisms. Therefore, the microbial ecology of an environment populated with microorganisms is best represented by biofilm communities rather than by organisms that are planktonic or “free-floating”. The most common current method for detecting the presence and types of bacteria, fungi, and other microorganisms in an aqueous environment consists of placing a series of “coupons” at various points in the system. Coupons are generally relatively small plastic strips to which bacteria and other microorganisms attach to form biofilms. Typically, these coupons must remain in a body of water for a long period of time in order to have an adequate amount of microbial biomass attach to facilitate analysis of the biofilm community. The time required to form biofilms depends on the quality of the water and a number of environmental factors but incubation times of weeks or months are not uncommon. Shear forces and the lack of any attractants make coupons a relatively poor substrate for microorganisms to attach to. Another method of collecting representative biofilm communities and detecting the presence of specific types of microorganisms consists of placing glass wool in a perforated vial and placing the vial in the water. However, these glass wool devices suffer from the same slow and low uptake as the more conventional coupons.
It is therefore desirable to provide a method and device for rapid uptake of large amounts of microbial biomass in representative biofilms from a variety of aqueous environments.